TDC1000: problems about temperature measurement with tdc1000 and tdc7200

user3697981

Prodigy 30 points

Part Number: TDC1000
Other Parts Discussed in Thread: TUSS4470, TUSS4440

The temperature is 1 degree lower than the thermometer. The waveform confirms this.I have read snaa230.pdf .
The temperature changes greatly in the measurement process.
The measuring environment is constant temperature in still water chamber，thanks.

over 5 years ago

0 Akeem Whitehead over 5 years ago

TI__Mastermind 27950 points

The only support available for this issue is what is listed in the TDC1000 FAQ (https://e2e.ti.com/support/sensors/f/1023/t/724028?TDC1000-Everything-You-Need-to-Know-for-Ultrasonic-ToF-Liquid-Coupled-Collateral-Tools-Designs-FAQ-):

Why are my temperature readings incorrect on the GUI?

This situation is caused by erroneous short pulses generated when measuring the resistance of the RTD. The mechanism and workaround for this behavior is described in the following application note:

Measuring an RTD Sensor with the TDC1000 and TDC7200 for Ultrasonic Sensing: www.ti.com/.../snaa230.pdf

When measuring the temperature value with the TDC1000-TDC7200 GUI ensure that the TEMP_MODE on the TDC1000 page is set to "REF_RTD1_RTD2", and that TEMP_RTD_MODE on the TEMPERATURE page is set to "RTD1 and RTD2" regardless of whether one or two RTDs are being measured at that time. The GUI automatically implements the workaround to provide the correct reading for RTD1.

An alternative solution is to use an external temperature sensor: http://www.ti.com/sensors/temperature-sensors/products.html

0 user3697981 over 5 years ago in reply to Akeem Whitehead

Prodigy 30 points

I've read this document before and applied it.
Will three wire PT1000 affect the accuracy？
Do we have to use two-wire PT1000 here？

0 Akeem Whitehead over 5 years ago in reply to user3697981

TI__Mastermind 27950 points

user3697981,

I have only seen two-wire PT1000 and PT500 RTD types used with the TDC1000. Please see these other E2E discussions to help troubleshoot your temperature measurement error:

Note: we have released a new TUSS44x0 series of improved performance ultrasonic devices to displace the TDC1000. We recommend switching to the TUSS4470 and TUSS4440 for full-bridge and transformer drive respectively.

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TDC1000: problems about temperature measurement with tdc1000 and tdc7200